201680

SI Motion CU: Checksum error safety monitoring functions

Siemens · DAsl Diagnostics and Alarms

What does 201680 mean?

The checksum calculated by the drive for safety-relevant parameters (r9728) does not match the reference checksum (p9729) saved during the last machine acceptance. This indicates that safety-relevant parameters have been altered or an internal fault is present, compromising the integrity of the safety monitoring functions. This fault results in a STOP A that can be acknowledged.

Common Causes

  • Accidental or unauthorized modification of safety-relevant parameters (e.g., P9700, P9701) after machine acceptance.
  • Data corruption in the non-volatile memory of the Control Unit (CU) storing safety parameters.
  • Firmware update on the Control Unit that affects safety parameter storage without re-acceptance.
  • Incorrect procedure for saving or restoring safety-relevant parameters, leading to mismatch between r9728 and P9729.

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Access safety parameters (e.g., P9700) using STARTER or TIA Portal and verify they match the last accepted machine configuration.

  2. 2

    Perform a 'Safety Acknowledge' (e.g., P10_9700=2) to re-evaluate the safety checksums if no parameters were changed.

  3. 3

    If parameters were intentionally changed, conduct a new safety acceptance test and save the new reference checksum (P9729).

  4. 4

    Reload the last valid safety project (configuration and parameters) into the Control Unit from a backup.

  5. 5

    If persistent, replace the Control Unit (CU) as its internal memory might be corrupted.

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Verified technical data. Last updated: March 2026

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Source: Siemens DAsl Diagnostics and Alarms